What weather condition is typically associated with cumulonimbus clouds?

Cumulonimbus clouds are towering clouds often associated with significant weather events due to their vertical development and moisture content. These clouds are a key indicator of thunderstorms, which may include heavy rain, strong winds, lightning, and hail. The formation of cumulonimbus clouds requires strong upward air currents that can lead to the formation of convection currents, resulting in localized thunderstorms.

The other listed weather conditions do not appropriately represent what is typically associated with cumulonimbus clouds. Clear skies suggest a lack of significant cloud cover and weather activity, thick fog indicates a low visibility condition caused by water vapor close to the ground, and gentle rain is usually associated with stratus or nimbostratus clouds rather than the severe weather phenomena characterized by cumulonimbus. Thus, thunderstorms are the primary weather condition linked to the presence of cumulonimbus clouds.